Supersensitized photographic silver halide emulsions



March 16, 1965 N. w. KALENDA 3,173,791

SUPERSENSITIZED PHOTOGRAPHIC SILVER HALIDE EMULSIONS Filed Sept. 27, 1962 2 Sheets-Sheet 1 hm 111 nml l ml 1m hm m l ll l l llll lill 1m nu 1111: WWW m1 m1 m1 SILVER BROMOIODIDE WITH SENSITIZERS Icndm Normanw' Kalenda By WZdd/INV TOR.

.ITIDRNEY 5 AGENT March 16, 1965 N. w. KALENDA 3,173,791

SUPERSENSITIZ-ED EHOTOGRAPHIC snvsa HALIDE EMULSIONS 2 Sheets-Sheet 2 Filed Sept. 27. 1962 m w w w m UUZQPUM EUE .PZMUKUL WAVELENGTH OF LIGHT IN mp United States Patent SUPERSENSITIZED PHGTOGRAPHIC SILVER HALEE EMULSIONS Norman W. Kalenda, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Sept. 27, 1962, Ser. No. 226,591 9 Claims. (Cl. 961t 4) This invention relates to photographic silver halide emulsions containing certain benzimidazolocarbocyanine dyes and in particular to silver halide emulsions containing supersensitizing combinations of bcnzimidazolocarbocyanines and bridged naphthimidazolooxacarbocyanine dyes and bridged benzimidazolooxacarbocyanine dyes.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class alter the sensitivity of photographic gelatino-silver halide emulsions when the dyes are incorporated in the emulsions. It is known that the sensitization produced by a given dye varies somewhat with the type of emulsion in which the dye is incorporated. Furthermore, the sensitization produced by a given dye in a given emulsion may be altered by changing the conditions of the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration or both. Thus, sensitization of plates can be increased by bathing plates coated with spectrally sensitized emulsions in water or aqueous solutions of ammonia. Such a process of altering the sensitivity of a sensitized emulsion by increasing the silver ion concentration or decreasing the hydrogen ion concentration is commonly called hypersensitization. Hypersensitized emulsions generally have poor keeping qualities.

I have discovered a means for increasing the sensitivity of photographic silver halide emulsions containing certain benzimidazolocarbocyanine dyes. Since the conditions of the hydrogen ion and silver ion concentrations are not changed appreciably by my method, I shall designate my new method as a kind of supersensitization.

It is, therefore, an object of my invention to provide photographic silver halide emulsions containing certain benzimidazolocarbocyanine dyes and in supersens-itizing combination therewith certain bridged naphthimidazolo oxacarbocyanine dyes.

Another object is to provide such supersensitized emulsions which are characterized by having single mixed aggregate sensitivity maxima at wavelengths between those of the emulsions sensitized with the dyes individually.

Another object is to provide a means for preparing such supersensitized emulsions.

Still other objects will become apparent from the following specification and claims.

These and other objects are accomplished according to my invention by adding to photographic silver halide emulsions supersensitizing combinations of certain benzimidazolocarbocyanine dyes with certain bridged naphthimidazolooxacarbocyanine dyes.

Included among the benzimidazolocarbocyanine dyes used to advantage according to my invention are those represented by the formula:

in which Y and Y each represent a hydrogen atom, a halogen atom, such as chlorine, bromine, iodine, etc., an

3,173,791 Patented Mar. 16, 1965 acetyl group, etc.; R represents an alkyl group, such as methyl, ethyl, propyl, butyl, etc., a carboxyalkyl group, such as carboxyethyl, carboxypropyl, etc.; R represents an alkyl group, such as methyl, ethyl, propyl, butyl, etc., and sulfoalkyl, such as 2-sulfoethyl, 3-sulfopropyl, 3-sulfobutyl, 4-sulfobutyl, etc.; and X represents an acid anion, such as chloride, iodide, bromide, perchlorate, p-toulenesulfonate, ethylsulfate, etc.

Included among the bridged an'midazolooxacarbocyanine dyes used according to my invention are those represented by the formula:

in which Z represents the nonmetallic atoms necessary to complete a nucleus of the arimidazole series, such as benzimidazole, 4-chlorobenzimidazole, S-bromobenzimidazole, 6-rnethylbenzimidazo1e, 7-methoxybenzimidazole, 5 acetoxybenzimidazole, 6 acetylbenzimidazole, naphth- (2,3-d)imidazo-le, 4 chloronaphth(2,3 d)imidazole, 5- bromonaphth(2,3 d-imidazole, 7 bromonaphth (25 d)- imidazole, 8 methylnaphth(2,3 d)imidazole, 9 ethylnaphth(2,3 d) imidazole, 5 acetoxynaphth(2,3 d)- imidazole, 6 acetylnaphth(2,3 d)imidazole, 6 phenylnaphth(2,3 d)imidazole, 5 sulfonaphth(2,3 d)imidazole, etc., a nucleus of the naphth(l,2-d)imidazole series, such as naphth(l,2-d)imidazole, 4 chloronaphth(1,2-d)- imidazole, 5 bromonaphth(l,2-d)imidazole, 6 methylnaphth( l,2-d)imidazole, 8 -ethylnaphth(1,2-d)imidazole, 7-acetoxynaphth( l,2-d)imidazole, 6 acetylnaphth(1,2 d)imida.zole, etc.; a nucleus of the naphth(2,l-d)imidazole series, such as 6-chloronaphth(2,1-d)imidazole, naphth- (2,l-d)imidazole, etc; R represents an alkyl group, suchas methyl, ethyl, propyl, butyl, etc.; R represents an alkyl group, such as methyl, ethyl, propyl, butyl, etc., and a sulfoalkyl group, such as 2-sulfoethyl, 3-sulfopropyl, 3- sulfobutyl, etc.; X represents an acid anion as defined previously; and n represents an integer of from 2 to 3.

Included among the benzimidazolocarbocyanine dyes of Formula I are the following typical examples.

DYE I DYE H (ll 2H5 5,5 ,6,6'-tetrachloro-1,1,3,3-tetraethylbenzimidazolocarbocyanine iodide 5,5-dibromo-1,1Q3,3 tetraet yllbenzimidazolocarbocyanine Anhydro-Ll'di(B-carboxyethyl)-5,5',6,6 tetrach10ro-3,3-

diethylbenzimidazolocarbocyanine hydroxide Included among the naphthimidazolooxacarbocyanine dyes'of Formula Here the following typical examples.

DYE VII 3,8-diethy1-1,IO-ethylenenaphth (2,3-(1) -imidazo1ooxacarbocyanine iodide 3,3 -diethy1-1,10-ethy1enenaphth(1,2-d) -imidazolooxacarb'ocyanine iodide 3,3'-diethy1-1,10-trimethylenenaphth (2,3-t1) -imidazo1ooxaearbocyanine iodide N N HZ -2 5 i! has 03 Anhydro-3-ethy1-1,10'ethy1ene3 (3-su1fobuty1) -naphth [2,3-d] imidazolooxacarbocyanine hydroxide Illustrative of the benzimidazole dyes included in the arimidazole dyes of Formula 11 used according to my invention is the following typical example.

t5,6-dichloro3,3-diethyl-1,S ethylenebenzimidazolooxacarbocyanine iodide According to my invention, I incorporate in a photographic emulsion one or more of the benzimidazolocarbocyanine dyes represented by Formula I and one or more of the bridged naphthimidazolooxacarbocyanine dyes represented by Formula II. My invention is particularly directed to the ordinarily employed gelatino-silver halide,

,e.g., gelatino-silver chloride, -chlorobromide, -chloroiodide, -chlorobromoiodide, -bromide, etc., developing-out emulsions. However, my supersensitizing combinations can be employed in siiver halide emulsionsin which the carrier or vehicle is other than gelatin, e.g., a resinous material such as polyvinyl alcohol, albumin, etc., or a hydrophilic cellulosic material which has no deleterious effect on the light-sensitive silver halide.

The concentration of the dyes used in my emulsions can be varied considerably depending upon the particular dyes used, the emulsion and the particular results desired. The optimum concentrations and ratio of the dyes in the supersensitizing combination can be determined by methods well .known in the art, in which the sensitivity is determined for a series of test portions of the emulsion desired, each portion containing a different concentration of the dyes.

Photographic silver halide emulsions, such as those described, containing the supersensitizing combinations of my invention can also contain such addenda as chemical sensitizers, e.g., sulfur sensitizers (e.g., allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, etc.), various gold compounds (e.g., potassium chloroaurate, auric trichloride, etc.) (see Baldsiefen US. Patent 2,540,085, issued February 6, 1951; Damschroder US. Patent 2,597,- 856, issued May 27, 1952, and Yutzy et al. US. Patent 2,597,915, issued May 27, 1952), various palladium compounds, such as palladium chloride (Baldsiefen US. Patent 2,540,086, issued February 6, 1951), potassium chloropalladate (Staufier et al. US. Patent 2,598,079, issued May 27, 1952),, etc., or mixtures of such sensitizers; antifoggants, such as ammonium chloroplatinate (Trivelli et al. US. Patent 2,566,245, issued August 28, 1951), am-.

(see Mees, The Theory of the Photographic Process,

MacMillan Pub.,'1942, page 460), or mixtures thereof;

hardeners, such as formaldehyde (Miller U.S. Patent 1,763,533, issued June 10, 1930), chrome alum (1,763,- 533), glyoxal (Brunken US. Patent 1,870,354, issued August 9, 1932), dibromacrolein (Block et al. British Patent 406,750, accepted March 8, 1934), etc.; color couplers, such as those described in Salminen et al. US. Pat ent 2,423,730, issued June 7, 1947, Spence and Carroll US. Patent 2,640,776, issued June 2, 1953, etc; or mixtures of such addenda. Dispersing agents for color couplers, such as those set forth in Jelley et al. US. Patent 2,322,027, issued June 15, 1943, and Mannes et al. US. Patent 2,304,940, issued December 15, 1942, can also be employed in the above described emulsions.

My invention is still further illustrated by the following examples.

Example 1 A silver bromoiodide emulsion was made of the type described by Trivelli and Smith, Phot. Journal, vol. 79, 330 (1939). The melted emulsion was divided into separate portions to which were added a solution of the sensitizer or combination of sensitizers indicated in Table 1. After being digested at 50 C. for minutes each of the portions of the sensitized emulsions was coated on a support and dried. The reflectance spectra of the coatings were plotted for light in the visual region with a General Electric Recording Spectrophotometer. The absorption maximums obtained from these curves are listed in the following table.

TABLE 1 Dye and concentration Absorption maxi (gm/mole of silver) mum in mp I (0.20) 580 I 0.20 +vn 0.15 572 v11 0.15) 550 I (0.20)+vn1 (0.15 569 I (0.20) -i-IX (0.074) 568 I (0.20)+x (0.15 566 VIII 0.15 518 IX (0.15) 550 X (0.15) 536 II (0.049) 575 II (0.049)+vn 0.049 568 VII (0.049) 548 My dye combinations illustrated in Table 1 exhibit single mixed aggregate maxima at wavelengths between those of the dyes used individually. This characteristic is of special importance in materials for color photography where the benzimidazolocarbocyanine dyes alone tend to sensitize too deeply for the best color reproduction.

Example 2 p-Methylaminophenol sulfate g 2 Sodium sulfite, desiccated g 90 Hydroquinone g 8 Sodium carbonate monohydrate g 52.5 Potassium bromide g 5 Water to make 1 liter.

fixed in a conventional sodium thiosulfate fixing bath, washed and dried. Dcnsitometric measurements through a Wratten #12 filter were made of the developed images on each coating. The relative speed values were calculated based on an arbitrary relative speed of 100 for the coating sensitized with 0.20 g. of Dye I per mole of silver and the gammas were determined. These values along with the fog values are shown in Table 2.

TABLE 2 Dye and Concentration (gJmole oi Relative Gamma Fog silver) Speed Example 3 Coatings were made as in Example 1 excepting that sensitize-rs 1, VIII, IX, X and combinations of I with each of the others were used. These coatings were exposed, processed, the density measurements made and the reactive speeds, gammas and fog values determined as in Example 2. These values are listed in Table 3.

TABLE 3 Dye and Concentration (g/molo of Relative Gamma Fog silver) Speed I (0.1 80 3. 58 10 I (0.2 100 2. 84 .08 I (0.10 115 2. 00 .08 I (0.10) 178 2.88 .10 I (0.10) I18 3. 10 08 I (0.10) 118 2. 62 08 I (0.10) 123 3. 10 10 VIII 20. 5 1. 12 10 VIII 29. 5 1. 81 13 IX (0. 43. 0 3. 66 .08 IX .15 49.0 3. 36 .10 X (0. 31.0 1.35 .08 X (0. 39.0 2. 86 I0 This table shows that my supersentizing dye combinations produce relative speeds as high as 178 by combining dyes which individually produce relative speeds of 80 and 29.5.

Example 4 Coatings were made, exposed and processed as in Example 2 excepting that sensitizers II and VII and a combination of them were used. Densitometric measurcments were made and the relative speeds, gammas and fog values are listed in the following table.

TABLE 4 Dye and Concentration (gjmole of Relative Gamma Fog silver) Speed II (0.0 I00 2. 44 07 II (0.049)+VII (0 049) 138 2 20 .10 VII (0 49) 83 1 10 .07

Example 5 Coatings were made as in Example 1 excepting that the dyes indicated in Tables 5, 6 and 7 were used. These coatings were exposed, processed, and the density measurements made through a yellow Wratten #15 filter for coatings in Table 5 and Table 6, and through a green Wratten #61 filter for coatings in Table 7. The relative speed, gammas, and fog values were determined and are listed in Tables 5, 6 and 7.

TABLE 6 Dye md Concentration Absorption Relative (gJmole of silver) Maximum Speed Gamma Fog (0.1) 567 69 1. 32 08 IV (0.2) 567 100 1. 80 .08 IV (0.1)-l-VII (0.1) 557 151 2.14 .08 VII (0.1) 548 107 1. 53 08 TABLE 7 Dye and Concentration Absorption Relative (gJmole of silver) Maximum Speed Gamma Fog IV (0. 567 48 1. 40 08 IV 567 63 2. 04 .08 IV (0 564, 510 120 2. 00 V (O. 573 69 2. 04 06 V (0.2) 573 100 2. 40 07 V (0.1)-l-VIII 558, 517 151 2. 22 .07 VI (0. 574 01 2. 28 .08 VI (0. 574 118 2. 18 08 VI (0.1)+VIII (0.1) 570, 516 170 2. 34 08 VI (0.1)+VII (0.1) 567 151 2. 28 .08 III (0. 567 l 95 1. 38 .05 XI (0. 544 1 155 1. 06 XI (0. 533 1 91 1. 18 06 1 Relative Speed determined from density measurements made throu gh Wratten #16+#6l filters.

My invention is still further illustrated by references to or descriptions of the preparations of representative dyes used in my supersensitizing combinations.

Dye XI was prepared by the method described hereinafter for Dye VII excepting that an equimolar amount of 5,6 dichloro 3 ethyl 1,2 trimethylenebenzirnidazolium iodide was used in place of 3-ethyl-1,2-trimethylenenaphth[2,3-d]imidazoliurn iodide.

Dyes II and IV are described in Van Lare U.S. Patent 2,739,149, issued March 20, 1956, as Examples 2 and 1, respectively. Dyes III and V are described in Brooker et al. US. Patent 2,778,823, issued January 22, 1957, as Examples 3 and 1, respectively.

:Dye VI was prepared as follows: 5,6-dichloro-1-ethyl- Z-methylbenzimidazol-e (2 mols, 4.5 g.) and B-iodopropicnic acid (1 mol, 2 :g.) were mixed and heated on a steam bath for four hours at which time the sticky mass that formed was stirred with an excess of ether, the ether was decanted, and the residue disolved in a solution of sodium alcoholate which was prepared by dissolving sodium (25 mols, .58 g.) in absolute ethyl alcohol, 50 mol. At this point, 2,2,2-trichloro-1-ethoxyethanol (.5 mol, .49 g.) was added and the mixture heated under reflux for 45 minutes. The mixture was then chilled and the solid dye along with colorless byproducts, were filtered off, the solids and dye stirred with an excess of Water, filtered oil, the solids and dye stirred with an excess of water, filtered off, stirred with methyl alcohol containing sodium iodide, 2 g, filtered oil and dried. Alter two recrystalizations by dissolving in methyl alcohol containing several drops of triethylamine and precipitated with acetic acid, the yield of pure Dye VI was .45 g. (15%) M.P. 227229 C. dec.

DYE VII 3-ethyl-1,Z-trimethylennaphth[2,3 dJimidazolium iodide (1 mol, 0.91 g.), 2-,8-acetanilidovinyl-3-ethylbenzoxwith acetone and dried. After two recrystallizati-ons from methyl alcohol, the yield of pure dye w-as 0.5 g. M.P. 301 .302 C. dec. r

8 i DYE VIII l-etl1yl-2,3-trimcthylenen aphth[1,2 d]imidazolium ptoluenesulfate (1 mol., 2.04 g.), 2-B-acetanilidovinyl-3- ethylbenzoxazolium iodide (1 mol., 2.17 g.) and triethylamine (2 mols, 1.4 ml.) were dissolved in dry pyridine (20 ml.) and heated under reflux for ten minutes. The reaction mixture was then chilled, crystalline dye filtered off, washed with acetone and dried. After two recrystallizations from methyl alcohol, the yield of pure dye was 0.6 g. (22%) M.P. 305306 C. dec.

DYE IX DYE X Anhydro-3-(3-sulfobutyl)-1,2 trimethylenenaphth[2,3- d]-imidazolium hydroxide (1 mol., 3.44 g.), Z- B-acetanilidovinyl-3-etl1ylbenzoxazoliurn iodide (1 mol., 4.36 g.) and triethylamine (2 mols; 2.8 ml.) were dissolved in dry pyridine (60 m1.) and heated under reflux for ten minutes. The reaction mixture was then chilled and the crude dye precipitated by adding an excess of ether with stirring. The solid dye was filtered off, washed with water and dried. After two recryst-allizations from pyridine, the yield of pure dye was 0.9g. (14%) M.P. 298-299 C. dec.

The accompanying drawings FIGS. 1, 2, 3 and 4 further illustrate my invention.

FIG. 1 is a wedge spectrogram for a silver bromoiodide emulsion sensitized with Dye I, anhydro-5,5',6,6-tetrachloro-l,l'-diethyl-3,3-di(3 sulfobutyl) benzimidazolo 'carbocyanine hydroxide at a concentration of 0.20 g. per

mole of silver halide.

FIG. 2 is a wedge spectrogram for a silver bromoiodide emulsion sensitized with Dye VIII, 3,3'-diethyl-1,10ethylenenapl1th(1,2-d)imidazolooxacarbocyanine iodide-at a concentration of 0.15 g. per mole of silver halide.

FIG. 3 is a wedge spectrogram for a silver bromoiodide emulsion containing a supersensitizing combination of Dye I and Dye VIII at concentrations of 0.20 g. and 0.15 g. per mole of silver halide, respectively.

FIG. 4 shows curves A, B and C, which relate the percent reflectance of light byv emulsion coatings containing a dye(s) with the wavelength of light being reflected. Curve A shows this relationship for an emulsion with the Dye I at a concentration of 0.20 g. per mole of silver halide. Curve C shows this relationship for an emulsion containing the Dye VIII at a concentration of 0.15 g. per mole of silver halide. Curve B shows this relationship for an emulsion containing a mixture of the dyes represented by Curves A and C, i.e., Dye I at a concentration of 0.20 g. per mole of silver halide and Dye VIII at a concentration of 0.15 g. per mole of silver halide, respectively.

These curves illustrate the valuable property characterizing combinations of certain of my dyes which exhibit single mixed aggregate absorption maxima (reflection minima) at wavelengths between those of the dyes used individually. It can be seen that the Curve B has a single reflection minimum at 572 mu. which is between the.

minimum of 580 mp for Curve A and the minimum of 550 m for Curve C.

My supersensitizing combinations of benzimidazolocarbocyanine dyes with N,u-a-lkylene bridged naphthimidan olooxacarbocyanine dyes are valuable for use in photographic silver halide emulsions.

The invention has been described in detail with particular reference to preferred embodiments thereof but it will be understood that variations and modifications can be eifected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A photographic silver halide emulsion containing a supersensitizing combination of a benzirnidazolocarbocyanine dye with a dye selected from those having the formula:

69 t f Ra Ra wherein Z represent the nonmetallic atoms necessary to complete a nucleus selected from the class consisting of a benzimidazole, a naphth(2,3-d)imidazole, a naphth(1,2- d)imidazole, and a naphth-(2,1-d)imidazole; R represents a member selected from the class consitsing of an alkyl group and a sulfoalkyl group; R represents an alkyl group; X- represents an acid anion; and n represents an integer of from 2 to 3.

2. A photographic silver halide emulsion containing a supersensitizing combination of a dye selected from those having the formula:

complete a nucleus selected from the class consisting of a benzirnidazole, a naphth(2,3-d)imidazole, a naphth(1,2- d)imidazole, and a naphth(2,1-d)imidazole; R represents a member selected from the class consisting of an alkyl group and a sulfoalkyl group; R represents an alkyl group; X represents an acid anion; and n represents an integer of from 2 to 3.

3. A photographic silver halide emulsion containing a s-upersensitizing combination of anhydro-5,5-,6,6'- tetrachloro 1,1 diethyl-3,3-di(3sulfobutyl)benzimidazolocarbocyanine hydroxide With 3,3'-diethyl-1,10-ethylenenaphth( 1,Z-d)imidazolooxacarbocyanine iodide.

4. A photographic silver halide emulsion containing a supersensitizing cornbinaation of 5,5',6,6-tetrach1oro- 1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide with 3,3-diethyl 1,10 ethylenenaphth(2,3-d)imidazolooxacarbocyanine iodide.

5. A photographic silver halide emulsion containing a supersensitizing combination of 5,5-dibromo-1,1,3,3- tetraethylbenzirnidazolocarbocyanine iodide with 3,3'-diethyl 1,10 ethylenenaphth(2,3-d)imidazolooxacarbocyanine iodide.

6. A photographic silver halide emulsion containing a supersensitizing combination of 5,5'-dichloro-'1,1,3,3- tetraethylbenzimidazolocarbocyanine iodide with 3,3'-diethyl 1,10 ethylenenaphth(2,3-d)imidazolooxacarbocyanine iodide.

7. A photographic silver halide emulsion containing a supersensitizing combination of anhydro-LY-dMB-carboxyethyl) 5,5',6,6' tetrachloro-3,3'-diethylbenzimidazolocarbocyanine hydroxide with 3,3'-diethyl-l,10-ethy1- enenaphth( 1,2-d imidazolooxacarbocyanine iodide.

8. A photographic element comprising a support coated With at least one layer containing a photographic silver halide emulsion of claim 1.

9. A photographic element comprising a support coated with at least one layer containing a photographic silver halide emulsion of claim 2.

References Cited in the file of this patent UNITED STATES PATENTS 2,954,376 Nys et al Sept. 27, 1960 2,973,264 Nys et al. Feb. 28, 1961 FOREIGN PATENTS 587,434 Great Britain Apr. 25', 1947 615,205 Great Britain Jan. 4, 1949 

1. A PHOTOGRPAHIC SILVER HALIDE EMULSION CONTAINING A SUPERSENSITIZING COMBINATION OF A BENZIMIDAZOLECARBOCYANINE DYE WITH A DYE SELECTED FROM THOSE HAVING THE FORMULA: 